EP3226051B1

EP3226051B1 - Lens, lens unit, and imaging device

Info

Publication number: EP3226051B1
Application number: EP15864176.1A
Authority: EP
Inventors: Hiroshi Okada; Katsumi Tsuji; Yasushi Koshiba; Takatoshi Nakata
Original assignee: Kyocera Corp
Current assignee: Kyocera Corp
Priority date: 2014-11-27
Filing date: 2015-11-27
Publication date: 2020-12-23
Anticipated expiration: 2035-11-27
Also published as: US20170329131A1; US10705330B2; EP3226051A4; WO2016084390A1; JPWO2016084390A1; EP3226051A1; JP6422506B2

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of Japanese Patent Application No. 2014-240359 (filed on November 27, 2014 ).

TECHNICAL FIELD

This disclosure relates to a lens, a lens unit, and an imaging apparatus.

BACKGROUND

There is conventionally known a structure fixing a lens with a fixing member (a retainer).
As an example, US 2010/177409 A1 discloses an optical element, comprising: an optical lens, having a first mirror and a second mirror, wherein a radius of curvature of the first mirror is smaller than a radius of curvature of the second mirror; and a holder, having an outer surface, an inner surface, and at least one groove, wherein the groove surrounds the inner surface, the optical lens is adhered to the inner surface, embedded in the groove, and fixed in the holder, the groove has a guiding face and a carrying face, the guiding face is obliquely disposed in a direction from the first mirror to the second mirror and from the inner surface of the holder to the outer surface, and the carrying face is perpendicular to the inner surface, and forms an oblique angle with the guiding face.
As a second further example, US 2005/063074 A1 discloses a holder and optical element device including a holder having a substantially cylindrical interior shape and an optical element fitted in the holder along an inner surface of the holder, wherein the holder may have a step on the inner surface thereof, and wherein this step has a surface that is inclined downward and inward from the interior surface of the holder, and wherein the optical element may have a convex optical surface section on a surface thereof and a flat surface section around the optical surface section, the flat surface section being disposed on the downward-inclined surface, and wherein the optical element is disposed on the inner surface of the holder in such a manner that the step is in contact with the peripheral surface of the optical element.
As a third further example, EP 2357503 A1 discloses a lens unit and a vehicle-mounted infrared lens unit capable of correcting a focal shift due to a temperature change without increasing the apparatus size, complicating a production process, and increasing the costs. The lens comprises a lens body comprising a cylindrical surface along the optical axis and a fixed portion radially outwardly protruding from the lens body. A lens barrel and spacer are arranged radially outside the cylindrical surface for holding the lens. A lens retainer is fixed to the lens barrel and in contact with the fixed portion.
As a fourth further example, JP 2012/163875 A discloses a lens fixing structure excellent in impact resistance from a subject side and a wide-angle imaging apparatus using the lens fixing structure, while attaining miniaturization of a lens unit The lens comprises an inclined portion. A barrel supports the lens and a pressing ring is fixed to the barrel and in contact with the inclined surface in order to fix the lens.
As a fifth further example, US 6388825 B1 discloses a support structure for positioning lens on a retention frame.
As a sixth further example, US 2010/027137 A1 discloses a lens module including a first lens, a second lens, a spacer, a seating part, and a protrusion part.
As a seventh further example, US 2014/247488 A1 discloses a lens, a lens unit and a lens manufacturing method.
As an eighth further example, US 2010/176281 A1 discloses an optical element incorporated into an imaging optical system.

SUMMARY

The present invention provides a lens unit according to independent claims 1 or 2 and an imaging apparatus according to claim 7. Further advantageous embodiments of the present invention are disclosed in dependent claims 3-6.

BRIEF DESCRIPTION OF THE DRAWINGS

In the accompanying drawings:

FIG. 1 is a cross-sectional side view illustrating a schematic configuration of a lens unit according to a first embodiment;
FIG. 2 is a a top view of a lens illustrating a contact area of an inclined surface of a lens of FIG. 1 in contact with a fixing member;
FIG. 3 is an enlarged view of a fixed portion of FIG. 1 and the vicinity thereof;
FIG. 4 is a cross-sectional side view illustrating a schematic configuration of a lens unit according to a second embodiment;
FIG. 5 is a top view of a lens illustrating contact positions on the inclined surface of the lens of FIG. 4 in contact with the fixing member;
FIG. 6 is a cross-sectional side view illustrating a schematic configuration of a lens unit according to a third embodiment;
FIGS. 7A and 7B are top views of the lens illustrating variations of the contact area or the contact position of the inclined surface of the lens in contact with the fixing member; and
FIG. 8 is a functional block diagram illustrating a schematic configuration of an imaging apparatus having the lens unit of FIG. 1 or FIG. 4.

DETAILED DESCRIPTION

For example, however, when known lens unit is mounted in a moving body such as a vehicle, the lens unit possibly breaks upon strong impact applied thereto by a foreign substance. It could be helpful to provide a lens that is less likely to break, a lens unit, and an imaging apparatus.
Hereinafter, embodiments of the disclosure will be described in detail with reference to the accompanying drawings.

First Embodiment

As illustrated in FIG. 1, a lens unit 10 includes a lens 20, a lens holder 30, and a fixing member 40. The lens holder 30 and the fixing member 40 are screwed together by screw fitting. The lens unit 10 forms, on an image plane, a subject image of a subject outside the lens unit 10.
The lens 20 is supported by the lens holder 30. The lens 20 includes a lens body 21 and a fixed portion 22 radially outwardly protruding in a flange shape from the lens body 21. The fixed portion 22 diminishes in diameter (tapers) along an optical axis of the lens body 21 from an image side toward a subject side. The lens 20 is fixed, at the fixed portion 22, by the fixing member 40 pressing the lens against the lens holder 30 along an optical axis direction. The fixing member 40 is, for example, a retainer and includes a contact portion 41 in contact with the fixed portion 22.
The lens body 21 includes an outer periphery forming a cylindrical surface 23 along the optical axis direction and contiguous to a lens surface 25 on the subject side of the lens 20.
The fixed portion 22 includes an inclined surface 24. The inclined surface 24 is a plane formed, on the subject side of the fixed portion 22, tapering along the optical axis of the lens body 21 from the image side toward the subject side. The inclined surface 24 is contiguous to the cylindrical surface 23 of the lens body 21. According to the present embodiment, as illustrated in FIG. 1, the inclined surface 24 is linear in cross-section. The inclined surface 24, from the outer periphery of the fixed portion 22 to the cylindrical surface 23, forms a predetermined elevation angle θ with respect to a plane (a horizontal plane in FIG. 1) perpendicular to the optical axis direction.
According to the present embodiment, the contact portion 41 of the fixing member 40 is planar and in contact with the inclined surface 24 in its entirety. The fixed portion 22 is fixed at the inclined surface 24 having surface contact with the contact portion 41 of the fixing member 40 throughout a circumferential direction of the lens 20. FIG. 2 is a top view of the lens 20 illustrating a contact area of the inclined surface 24 of the lens 20 of FIG. 1 in contact with the fixing member 40. As illustrated in FIG 2, the lens 20, in the top view thereof, includes the lens surface 25 at the center thereof and the inclined surface 24 surrounding the lens surface 25. The lens 20 of the present embodiment is in contact with the fixing member 40 in an entire shaded area of the inclined surface 24 in FIG. 2. According to the present embodiment, that is, the lens 20 is fixed being pressed by the fixing member 40 in the shaded area in FIG. 2.
Having the inclined surface 24 as illustrated in FIG 1, the fixed portion 22 becomes thicker towards the center of the lens 20. Therefore, as compared to a lens 20 omitting the inclined surface 24, the lens 20 according to the present embodiment is more resistant to impact applied in the optical axis direction. Accordingly, the lens 20 of the present embodiment withstands impact caused by a foreign substance in the vicinity of a boundary between the fixing member 40 and the lens surface 25.
Also, having the inclined surface 24, the fixed portion 22 may disperse impulse force applied to the lens 20. FIG. 3 is an enlarged view of the fixed portion 22 and the vicinity thereof. In the present embodiment, as illustrated in FIG. 3, for example, when a foreign substance applies impact to the vicinity of the boundary between the fixing member 40 and the lens surface 25, the impulse force is generated in the optical axis direction (in a downward direction in FIG. 3) and travels through the fixing member 40 and reaches the fixed portion 22. Here, since the fixed portion 22 includes the inclined surface 24, the impulse force received by the fixed portion 22 may be dispersed into a direction along the inclined surface 24 and a direction orthogonal to the inclined surface 24, as illustrated in FIG. 3. In this way, the fixed portion 22, having the inclined surface 24, may disperse the impulse force applied in the optical axis direction. Accordingly, the lens 20 of the present embodiment is more resistant to impact as compared to the lens 20 omitting the inclined surface 24.
The elevation angle θ of the inclined surface 24 is appropriately set in accordance with design of the lens unit 10. Preferably, the elevation angle θ, as described above, makes the lens 20 more resistant to impact caused by the impulse force applied to the fixed portion 22 while dispersing the impulse force. The elevation angle θ is within a range of, for example, 10 degrees or more and smaller than 70 degrees. When the elevation angle θ is 10 degrees or larger, the impulse force applied in the optical axis direction is dispersed and, also, a thickness of the fixed portion 22 is increased. Therefore, the lens 20 is less likely to break. Also, when the elevation angle θ is smaller than 70 degrees, the fixing member 40 may fix the lens 20 on the lens holder 30. When the elevation angle θ is 70 degrees or larger, the lens 20 may not be appropriately fixed due to insufficient clamping by the fixing member 40.

Second Embodiment

FIG 4 is a cross-sectional side view illustrating a schematic configuration of a lens unit according to a second embodiment. In the second embodiment, the fixing member 40 includes a contact portion 41 having a step-like shape in cross-section. Hereinafter, descriptions of features the same as those of the first embodiment will be omitted, and different features will be described.
According to the present embodiment, protruding portions of the contact portion 41 protruding to the inclined surface 24 are in contact with the inclined surface 24. That is, the fixed portion 22 is fixed at the inclined surface 24 throughout a circumferential direction thereof having concentric continuous linear contact with the contact portion 41 centered at the optical axis. The lens 20 of the present embodiment, on the inclined surface 24 as indicated by broken lines in FIG. 5, is in contact with the fixing member 40 via two concentric lines centered at the optical axis throughout the circumferential direction. In the present embodiment, accordingly, the lens 20 is fixed being pressed by the fixing member 40 on the broken lines illustrated in FIG 5.
According to the present embodiment, also, the lens 20 includes the inclined surface 24. Similarly to the first embodiment, therefore, the lens 20 of the present embodiment is more resistant to impact as compared to the lens omitting the inclined surface 24. According to the present embodiment, also, when a foreign substance applies impact in the vicinity of the boundary between the fixing member 40 and the lens surface 25, the fixed portion 22 receives the impulse force on the lines in concentric contact with the lens surface 25. Therefore, the contact portion 41 may be designed to receive the impulse force applied by the foreign substance at a desired position on the fixed portion 22.

Third Embodiment

FIG. 6 is a cross-sectional side view illustrating a schematic configuration of a lens unit according to a third embodiment. According to the third embodiment, the lens unit includes four lenses: L1, L2, L3 and L4. The lenses L1, L2, L3 and L4 are held within the lens unit in a manner overlapping with each other in the mentioned order from the subject side to the image side. The lens L4 has a diameter larger than that of the lens L3, and the lens L3 has a diameter larger than that of the lens L2. The lens L2 has a diameter larger than a maximum diameter of the lens L1. The lens L1 includes the inclined surface 24 radially outwardly protruding from a body of the lens L1. The inclined surface 24 is tapered with respect to the optical axis of the body of the lens L1 from the image side to the subject side and contiguous to the cylindrical surface 23 of the body of the lens L1. Hereinafter, descriptions of features the same as those of the first embodiment will be omitted, and different features will be described.
According to the present embodiment, the lens L1 is fixed being pressed along the optical axis direction against the lens holder 30 located on the subject side via the lenses L2, L3 and L4. The fixing member 40 is in contact with an image-side surface of the lens L4 located closest to the image side among all the lenses.
According to the present embodiment, the inclined surface 24 of the fixed portion 22 is in contact with the lens holder 30. In the present embodiment, therefore, the lens L1 is pressed in the optical axis direction by the lens holder 30.
In an example illustrated in FIG 6, further, the lenses L1, L2, L3 and L4 together form a peripheral surface 26 having a step-like shape. On the peripheral surface 26, an edge portion of a surface perpendicular to the optical axis, i.e., respective edge portions of subject-side surfaces of the lenses L1, L2, L3 and L4 are out of contact with the lens holder 30, while surfaces of the lenses L1, L2, L3 and L4 parallel to the optical axis are in contact with the lens holder 30.
According to the present embodiment, the lens L1 includes the inclined surface 24. Similarly to the first embodiment, therefore, the lens L1 is more resistant to impact as compared to the lens omitting the inclined surface 24.
Note that the disclosure is not limited to the above embodiments but may be modified or changed in a variety of manners within the scope defined by the claims. For example, functions and the like of each constituent and the like may be rearranged without logical inconsistency, so as to combine a plurality of constituents together or to separate them.
For example, although in the second embodiment as described above the fixed portion 22 is in contact with the fixing member 40 at the two concentric lines centered at the optical axis because of the step-like shape of the contact portion 41, the contact between the fixed portion 22 and the fixing member 40 is not limited to the two concentric lines. Depending on a structure of the contact portion 41, the fixed portion 22 and the fixing member 40 may contact with each other at one, three, or more concentric lines.
Although in the second embodiment as described above the contact portion 41 has the step-like shape, the shape of the contact portion 41 is not limited thereto. The contact portion 41 may have any shape as long as being in contact with the inclined surface 24 of the fixed portion 22 at concentric lines centered at the optical axis.
Although in the first and second embodiments as described above the lens 20 is fixed by the fixing member 40 in the fixed portion 22 having the contiguous surface or linear contact with the fixing member 40, the contact between the fixed portion 22 and the fixing member 40 is not limited to contiguous contacts. The contact portion 41 may be designed to have intermittent contact with the inclined surface 24 in a circumferential direction of concentric lines centered at the optical axis such that the fixed portion 22 is in intermittent contact with the fixing member 40 on the inclined surface 24.
For example, it is assumed that the contact portion 41 of the fixing member 40 includes protruding planar portions protruding to the image side and having surface contact with the inclined surface 24 and recessed portions recessed from the image side and out of contact with the inclined surface 24, and that the planar protruding portions and the recessed portions are alternately formed along a circumference of the inclined surface 24. In this case, the planar protruding portions of the contact portion 41 formed intermittently has surface contact with the inclined surface 24. When four planar protruding portions are provided at equal intervals along the circumference, the inclined surface 24 and the fixing member 40 have intermittent surface contact with each other in shaded areas as illustrated by a top view of the lens 20 in FIG. 7A, by way of example.
It is assumed that, for example, the fixing member 40 includes the contact portion 41 with protruding portions and the recessed portions alternately formed along the circumference in a manner similar to the above example, and that the protruding portions form the step-like shape as described in the second embodiment. In this case, the contact portion 41 is in linear contact with the inclined surface 24 at the protruding portions intermittently protruding to the inclined surface 24. When four protruding portions are provided at equal intervals along the circumference, the inclined surface 24 and the fixing member 40 have intermittent linear contact with each other on broken lines as illustrated by the top view of the lens 20 in FIG. 7B, by way of example.
Although in the first and second embodiments as described above the inclined surface 24 forms a straight line in cross-section, the shape of the inclined surface 24 is not limited thereto. For example, the inclined surface 24 may curve in cross-section. The contact portion 41 of the fixing member 40 is appropriately designed according to the shape of the inclined surface 24 so as to have surface contact or linear contact with the inclined surface 24.
Although in the first and second embodiments as described above the fixing member 40 is the retainer, the fixing member 40 is not limited thereto. The fixing member 40 may have, for example, a caulking structure to fix the fixed portion 22 in a pressing manner.
Further, the lens unit 10 of the first and second embodiments as described above may be mounted in an imaging apparatus. FIG 8 is a functional block diagram illustrating a schematic configuration of an imaging apparatus having the lens unit 10. An imaging apparatus 60 includes the lens unit 10 described in the above first or second embodiment and an image sensor 50. The image sensor 50 captures a subject image formed on an image plane by the lens unit 10. When the imaging apparatus 60 as described above is mounted in a moving body and the like, the lens 20 having the inclined surface 24 withstands the impact caused by a foreign substance hitting the lens unit 10 of the imaging apparatus 60.

REFERENCE SIGNS LIST

10: lens unit
20, L1, L2, L3, L4: lens
21: lens body
22: fixed portion
23: cylindrical surface
24: inclined surface
25: lens surface
26: peripheral surface
30: lens holder
40: fixing member
41: contact portion
50: image sensor
60: imaging apparatus

Claims

A lens unit (10) comprising:
a lens (20) comprising:
a lens body (21) comprising a cylindrical surface (23) along an optical axis direction; and

a fixed portion (22) radially outwardly protruding from the lens body (21), comprising a diameter diminishing more and more from an image side toward a subject side along an optical axis of the lens body (21), and including an inclined surface (24) contiguous to the cylindrical surface of the lens body (21);

a lens holder (30) arranged at a radially outside of the cylindrical surface (23) and supporting the lens (20); and

a fixing member (40) coupled to the lens holder (30) and in contact with the inclined surface (24) so as to, together with the lens holder (30), fix the lens (20) in a manner pressing the lens (20) in the optical axis direction.
A lens unit (10) comprising:
a lens (L1) comprising:
a lens body (21) comprising a cylindrical surface (23) along an optical axis direction; and

a fixed portion (22) radially outwardly protruding from the lens body (21), comprising a diameter diminishing more and more from an image side toward a subject side along an optical axis of the lens body (21), and including an inclined surface (24) contiguous to the cylindrical surface (23) of the lens body (21) ;

a lens holder (30) arranged radially outside of the cylindrical surface (23) and in contact with the inclined surface (24) of the fixed portion (22) of the lens (L1) to support the lens (L1); and

a fixing member (40) coupled to the lens holder (30) and, together with the lens holder (30), fixing the lens (L1) in a manner pressing the lens (L1) in the optical axis direction.
The lens unit (10) according to claim 1 or 2, wherein the contact is surface contact.
The lens unit (10) according to claim 1 or 2, wherein the contact comprises concentric contiguous contacts which are centered on the optical axis.
The lens unit (10) according to claim 1 or 2, wherein the contact is intermittent in a circumferential direction and forms concentric lines centered at the optical axis.
The lens unit (10) according to claim 2, wherein
the lens unit (10) comprises three additional lenses (L2, L3, L4),
the diameters of the three additional lenses (L4 to L2) and the lens (L1) decrease sequentially, wherein the lens (L1) has the smallest diameter and the lens (L1) and the three additional lenses ( L2, L3, L4) are arranged such that the lens (L1) is arranged at the subject side.
An imaging apparatus (60) comprising:
the lens unit (10) according to any one of claims 1 to 6; and

an image sensor (50) for capturing a subject image formed by the lens unit (10).